ct dualism in the
organisation of society and, therefore, of the theoretical equality
between the ecclesiastical and the secular organs of government.
According to this doctrine Sacerdotium and Imperium are independent
spheres, each wielding the one of the two swords appropriate to
itself, and thus the Emperor no less than the Pope is Vicarius
Dei. It is this doctrine behind which the champions of the Empire
entrench themselves in their contest with the Papacy. It was asserted
by the Emperors themselves, notably by Frederick I and Frederick II,
and it has been enshrined in the writings of Dante.

[Sidenote: Its weakness.]

The weak point of this theory was that it was rather a thesis for
academic debate than a rallying cry for the field of battle. Popular
contests are for victory, not for delimitation of territory. And its
weakness was apparent in this, that while the thorough-going partisans
of the Church allowed to the Emperor practically no power except such
as he obtained by concession of or